* [PATCH 1/3] x86/alternatives: Teach text_poke_bp() to emulate instructions
2019-08-26 12:51 [PATCH 0/3] Rewrite x86/ftrace to use text_poke() Peter Zijlstra
@ 2019-08-26 12:51 ` Peter Zijlstra
2019-08-26 12:51 ` [PATCH 2/3] x86/alternatives: Move tp_vec Peter Zijlstra
` (2 subsequent siblings)
3 siblings, 0 replies; 7+ messages in thread
From: Peter Zijlstra @ 2019-08-26 12:51 UTC (permalink / raw)
To: linux-kernel, x86
Cc: Nadav Amit, Andy Lutomirski, Dave Hansen, Song Liu,
Masami Hiramatsu, Steven Rostedt, Daniel Bristot de Oliveira,
Peter Zijlstra
In preparation for static_call and variable size jump_label support,
teach text_poke_bp() to emulate instructions, namely:
JMP32, JMP8, CALL, NOP2, NOP_ATOMIC5
The current text_poke_bp() takes a @handler argument which is used as
a jump target when the temporary INT3 is hit by a different CPU.
When patching CALL instructions, this doesn't work because we'd miss
the PUSH of the return address. Instead, teach poke_int3_handler() to
emulate an instruction, typically the instruction we're patching in.
This fits almost all text_poke_bp() users, except
arch_unoptimize_kprobe() which restores random text, and for that site
we have to build an explicit emulate instruction.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/text-patching.h | 24 ++++++--
arch/x86/kernel/alternative.c | 98 ++++++++++++++++++++++++++---------
arch/x86/kernel/jump_label.c | 9 +--
arch/x86/kernel/kprobes/opt.c | 11 ++-
4 files changed, 103 insertions(+), 39 deletions(-)
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -26,10 +26,11 @@ static inline void apply_paravirt(struct
#define POKE_MAX_OPCODE_SIZE 5
struct text_poke_loc {
- void *detour;
void *addr;
- size_t len;
- const char opcode[POKE_MAX_OPCODE_SIZE];
+ int len;
+ s32 rel32;
+ u8 opcode;
+ const char text[POKE_MAX_OPCODE_SIZE];
};
extern void text_poke_early(void *addr, const void *opcode, size_t len);
@@ -51,8 +52,10 @@ extern void text_poke_early(void *addr,
extern void *text_poke(void *addr, const void *opcode, size_t len);
extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
extern int poke_int3_handler(struct pt_regs *regs);
-extern void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
+extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate);
extern void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries);
+extern void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
+ const void *opcode, size_t len, const void *emulate);
extern int after_bootmem;
extern __ro_after_init struct mm_struct *poking_mm;
extern __ro_after_init unsigned long poking_addr;
@@ -63,8 +66,17 @@ static inline void int3_emulate_jmp(stru
regs->ip = ip;
}
-#define INT3_INSN_SIZE 1
-#define CALL_INSN_SIZE 5
+#define INT3_INSN_SIZE 1
+#define INT3_INSN_OPCODE 0xCC
+
+#define CALL_INSN_SIZE 5
+#define CALL_INSN_OPCODE 0xE8
+
+#define JMP32_INSN_SIZE 5
+#define JMP32_INSN_OPCODE 0xE9
+
+#define JMP8_INSN_SIZE 2
+#define JMP8_INSN_OPCODE 0xEB
static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
{
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -956,16 +956,15 @@ NOKPROBE_SYMBOL(patch_cmp);
int poke_int3_handler(struct pt_regs *regs)
{
struct text_poke_loc *tp;
- unsigned char int3 = 0xcc;
void *ip;
/*
* Having observed our INT3 instruction, we now must observe
* bp_patching.nr_entries.
*
- * nr_entries != 0 INT3
- * WMB RMB
- * write INT3 if (nr_entries)
+ * nr_entries != 0 INT3
+ * WMB RMB
+ * write INT3 if (nr_entries)
*
* Idem for other elements in bp_patching.
*/
@@ -978,9 +977,9 @@ int poke_int3_handler(struct pt_regs *re
return 0;
/*
- * Discount the sizeof(int3). See text_poke_bp_batch().
+ * Discount the INT3. See text_poke_bp_batch().
*/
- ip = (void *) regs->ip - sizeof(int3);
+ ip = (void *) regs->ip - INT3_INSN_SIZE;
/*
* Skip the binary search if there is a single member in the vector.
@@ -997,8 +996,22 @@ int poke_int3_handler(struct pt_regs *re
return 0;
}
- /* set up the specified breakpoint detour */
- regs->ip = (unsigned long) tp->detour;
+ ip += tp->len;
+
+ switch (tp->opcode) {
+ case CALL_INSN_OPCODE:
+ int3_emulate_call(regs, (long)ip + tp->rel32);
+ break;
+
+ case JMP32_INSN_OPCODE:
+ case JMP8_INSN_OPCODE:
+ int3_emulate_jmp(regs, (long)ip + tp->rel32);
+ break;
+
+ default: /* nop */
+ int3_emulate_jmp(regs, (long)ip);
+ break;
+ }
return 1;
}
@@ -1027,8 +1040,8 @@ NOKPROBE_SYMBOL(poke_int3_handler);
*/
void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries)
{
+ unsigned char int3 = INT3_INSN_OPCODE;
int patched_all_but_first = 0;
- unsigned char int3 = 0xcc;
unsigned int i;
lockdep_assert_held(&text_mutex);
@@ -1056,7 +1069,7 @@ void text_poke_bp_batch(struct text_poke
for (i = 0; i < nr_entries; i++) {
if (tp[i].len - sizeof(int3) > 0) {
text_poke((char *)tp[i].addr + sizeof(int3),
- (const char *)tp[i].opcode + sizeof(int3),
+ (const char *)tp[i].text + sizeof(int3),
tp[i].len - sizeof(int3));
patched_all_but_first++;
}
@@ -1076,7 +1089,7 @@ void text_poke_bp_batch(struct text_poke
* replacing opcode.
*/
for (i = 0; i < nr_entries; i++)
- text_poke(tp[i].addr, tp[i].opcode, sizeof(int3));
+ text_poke(tp[i].addr, tp[i].text, sizeof(int3));
on_each_cpu(do_sync_core, NULL, 1);
/*
@@ -1087,6 +1100,53 @@ void text_poke_bp_batch(struct text_poke
bp_patching.nr_entries = 0;
}
+void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
+ const void *opcode, size_t len, const void *emulate)
+{
+ struct insn insn;
+
+ if (!opcode)
+ opcode = (void *)tp->text;
+ else
+ memcpy((void *)tp->text, opcode, len);
+
+ if (!emulate)
+ emulate = opcode;
+
+ kernel_insn_init(&insn, emulate, MAX_INSN_SIZE);
+ insn_get_length(&insn);
+
+ BUG_ON(!insn_complete(&insn));
+ BUG_ON(len != insn.length);
+
+ tp->addr = addr;
+ tp->len = len;
+ tp->opcode = insn.opcode.bytes[0];
+
+ switch (tp->opcode) {
+ case CALL_INSN_OPCODE:
+ case JMP32_INSN_OPCODE:
+ case JMP8_INSN_OPCODE:
+ tp->rel32 = insn.immediate.value;
+ break;
+
+ default: /* assume NOP */
+ switch (len) {
+ case 2:
+ BUG_ON(memcmp(emulate, ideal_nops[len], len));
+ break;
+
+ case 5:
+ BUG_ON(memcmp(emulate, ideal_nops[NOP_ATOMIC5], len));
+ break;
+
+ default:
+ BUG();
+ }
+ break;
+ }
+}
+
/**
* text_poke_bp() -- update instructions on live kernel on SMP
* @addr: address to patch
@@ -1098,20 +1158,10 @@ void text_poke_bp_batch(struct text_poke
* dynamically allocated memory. This function should be used when it is
* not possible to allocate memory.
*/
-void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
+void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate)
{
- struct text_poke_loc tp = {
- .detour = handler,
- .addr = addr,
- .len = len,
- };
-
- if (len > POKE_MAX_OPCODE_SIZE) {
- WARN_ONCE(1, "len is larger than %d\n", POKE_MAX_OPCODE_SIZE);
- return;
- }
-
- memcpy((void *)tp.opcode, opcode, len);
+ struct text_poke_loc tp;
+ text_poke_loc_init(&tp, addr, opcode, len, emulate);
text_poke_bp_batch(&tp, 1);
}
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -89,8 +89,7 @@ static void __ref __jump_label_transform
return;
}
- text_poke_bp((void *)jump_entry_code(entry), &code, JUMP_LABEL_NOP_SIZE,
- (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
+ text_poke_bp((void *)jump_entry_code(entry), &code, JUMP_LABEL_NOP_SIZE, NULL);
}
void arch_jump_label_transform(struct jump_entry *entry,
@@ -147,11 +146,9 @@ bool arch_jump_label_transform_queue(str
}
__jump_label_set_jump_code(entry, type,
- (union jump_code_union *) &tp->opcode, 0);
+ (union jump_code_union *)&tp->text, 0);
- tp->addr = entry_code;
- tp->detour = entry_code + JUMP_LABEL_NOP_SIZE;
- tp->len = JUMP_LABEL_NOP_SIZE;
+ text_poke_loc_init(tp, entry_code, NULL, JUMP_LABEL_NOP_SIZE, NULL);
tp_vec_nr++;
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -437,8 +437,7 @@ void arch_optimize_kprobes(struct list_h
insn_buff[0] = RELATIVEJUMP_OPCODE;
*(s32 *)(&insn_buff[1]) = rel;
- text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE,
- op->optinsn.insn);
+ text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE, NULL);
list_del_init(&op->list);
}
@@ -448,12 +447,18 @@ void arch_optimize_kprobes(struct list_h
void arch_unoptimize_kprobe(struct optimized_kprobe *op)
{
u8 insn_buff[RELATIVEJUMP_SIZE];
+ u8 emulate_buff[RELATIVEJUMP_SIZE];
/* Set int3 to first byte for kprobes */
insn_buff[0] = BREAKPOINT_INSTRUCTION;
memcpy(insn_buff + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+
+ emulate_buff[0] = RELATIVEJUMP_OPCODE;
+ *(s32 *)(&emulate_buff[1]) = (s32)((long)op->optinsn.insn -
+ ((long)op->kp.addr + RELATIVEJUMP_SIZE));
+
text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE,
- op->optinsn.insn);
+ emulate_buff);
}
/*
^ permalink raw reply [flat|nested] 7+ messages in thread* [RFC][PATCH 3/3] x86/ftrace: Use text_poke()
2019-08-26 12:51 [PATCH 0/3] Rewrite x86/ftrace to use text_poke() Peter Zijlstra
2019-08-26 12:51 ` [PATCH 1/3] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-08-26 12:51 ` [PATCH 2/3] x86/alternatives: Move tp_vec Peter Zijlstra
@ 2019-08-26 12:51 ` Peter Zijlstra
2019-08-26 15:13 ` Peter Zijlstra
2019-08-26 13:04 ` [PATCH 0/3] Rewrite x86/ftrace to use text_poke() Peter Zijlstra
3 siblings, 1 reply; 7+ messages in thread
From: Peter Zijlstra @ 2019-08-26 12:51 UTC (permalink / raw)
To: linux-kernel, x86
Cc: Nadav Amit, Andy Lutomirski, Dave Hansen, Song Liu,
Daniel Bristot de Oliveira, Steven Rostedt, Peter Zijlstra
Move ftrace over to using the generic x86 text_poke functions; this
avoids having a second/different copy of that code around.
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/ftrace.h | 2
arch/x86/kernel/ftrace.c | 571 +++---------------------------------------
arch/x86/kernel/traps.c | 9
3 files changed, 51 insertions(+), 531 deletions(-)
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -35,8 +35,6 @@ struct dyn_arch_ftrace {
/* No extra data needed for x86 */
};
-int ftrace_int3_handler(struct pt_regs *regs);
-
#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
#endif /* CONFIG_DYNAMIC_FTRACE */
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -43,16 +43,17 @@ int ftrace_arch_code_modify_prepare(void
* ftrace has it set to "read/write".
*/
mutex_lock(&text_mutex);
- set_kernel_text_rw();
- set_all_modules_text_rw();
+ WARN_ON_ONCE(tp_vec_nr);
return 0;
}
int ftrace_arch_code_modify_post_process(void)
__releases(&text_mutex)
{
- set_all_modules_text_ro();
- set_kernel_text_ro();
+ if (tp_vec_nr) {
+ text_poke_bp_batch(tp_vec, tp_vec_nr);
+ tp_vec_nr = 0;
+ }
mutex_unlock(&text_mutex);
return 0;
}
@@ -60,67 +61,36 @@ int ftrace_arch_code_modify_post_process
union ftrace_code_union {
char code[MCOUNT_INSN_SIZE];
struct {
- unsigned char op;
+ char op;
int offset;
} __attribute__((packed));
};
-static int ftrace_calc_offset(long ip, long addr)
-{
- return (int)(addr - ip);
-}
-
-static unsigned char *
-ftrace_text_replace(unsigned char op, unsigned long ip, unsigned long addr)
+static char *ftrace_text_replace(char op, unsigned long ip, unsigned long addr)
{
static union ftrace_code_union calc;
- calc.op = op;
- calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
+ calc.op = op;
+ calc.offset = (int)(addr - (ip + MCOUNT_INSN_SIZE));
return calc.code;
}
-static unsigned char *
-ftrace_call_replace(unsigned long ip, unsigned long addr)
-{
- return ftrace_text_replace(0xe8, ip, addr);
-}
-
-static inline int
-within(unsigned long addr, unsigned long start, unsigned long end)
+static char *ftrace_nop_replace(void)
{
- return addr >= start && addr < end;
-}
-
-static unsigned long text_ip_addr(unsigned long ip)
-{
- /*
- * On x86_64, kernel text mappings are mapped read-only, so we use
- * the kernel identity mapping instead of the kernel text mapping
- * to modify the kernel text.
- *
- * For 32bit kernels, these mappings are same and we can use
- * kernel identity mapping to modify code.
- */
- if (within(ip, (unsigned long)_text, (unsigned long)_etext))
- ip = (unsigned long)__va(__pa_symbol(ip));
-
- return ip;
+ return ideal_nops[NOP_ATOMIC5];
}
-static const unsigned char *ftrace_nop_replace(void)
+static char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
- return ideal_nops[NOP_ATOMIC5];
+ return ftrace_text_replace(CALL_INSN_OPCODE, ip, addr);
}
-static int
-ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code)
+static int;
+ftrace_modify_code_direct(unsigned long ip, const char *old_code,
+ const char *new_code)
{
- unsigned char replaced[MCOUNT_INSN_SIZE];
-
- ftrace_expected = old_code;
+ char cur_code[MCOUNT_INSN_SIZE];
/*
* Note:
@@ -129,31 +99,23 @@ ftrace_modify_code_direct(unsigned long
* Carefully read and modify the code with probe_kernel_*(), and make
* sure what we read is what we expected it to be before modifying it.
*/
-
/* read the text we want to modify */
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+ if (probe_kernel_read(cur_code, (void *)ip, MCOUNT_INSN_SIZE))
return -EFAULT;
/* Make sure it is what we expect it to be */
- if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+ if (memcmp(cur_code, old_code, MCOUNT_INSN_SIZE) != 0)
return -EINVAL;
- ip = text_ip_addr(ip);
-
/* replace the text with the new text */
- if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
- return -EPERM;
-
- sync_core();
-
+ text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE);
return 0;
}
-int ftrace_make_nop(struct module *mod,
- struct dyn_ftrace *rec, unsigned long addr)
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned const char *new, *old;
unsigned long ip = rec->ip;
+ const char *new, *old;
old = ftrace_call_replace(ip, addr);
new = ftrace_nop_replace();
@@ -166,20 +128,21 @@ int ftrace_make_nop(struct module *mod,
* We do not want to use the breakpoint version in this case,
* just modify the code directly.
*/
- if (addr == MCOUNT_ADDR)
- return ftrace_modify_code_direct(rec->ip, old, new);
+ if (addr == MCOUNT)
+ return ftrace_modify_code_direct(ip, old, new);
- ftrace_expected = NULL;
-
- /* Normal cases use add_brk_on_nop */
+ /*
+ * x86 overrides ftrace_replace_code -- this function will never be used
+ * in this case.
+ */
WARN_ONCE(1, "invalid use of ftrace_make_nop");
return -EINVAL;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned const char *new, *old;
unsigned long ip = rec->ip;
+ const char *new, *old;
old = ftrace_nop_replace();
new = ftrace_call_replace(ip, addr);
@@ -189,43 +152,6 @@ int ftrace_make_call(struct dyn_ftrace *
}
/*
- * The modifying_ftrace_code is used to tell the breakpoint
- * handler to call ftrace_int3_handler(). If it fails to
- * call this handler for a breakpoint added by ftrace, then
- * the kernel may crash.
- *
- * As atomic_writes on x86 do not need a barrier, we do not
- * need to add smp_mb()s for this to work. It is also considered
- * that we can not read the modifying_ftrace_code before
- * executing the breakpoint. That would be quite remarkable if
- * it could do that. Here's the flow that is required:
- *
- * CPU-0 CPU-1
- *
- * atomic_inc(mfc);
- * write int3s
- * <trap-int3> // implicit (r)mb
- * if (atomic_read(mfc))
- * call ftrace_int3_handler()
- *
- * Then when we are finished:
- *
- * atomic_dec(mfc);
- *
- * If we hit a breakpoint that was not set by ftrace, it does not
- * matter if ftrace_int3_handler() is called or not. It will
- * simply be ignored. But it is crucial that a ftrace nop/caller
- * breakpoint is handled. No other user should ever place a
- * breakpoint on an ftrace nop/caller location. It must only
- * be done by this code.
- */
-atomic_t modifying_ftrace_code __read_mostly;
-
-static int
-ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code);
-
-/*
* Should never be called:
* As it is only called by __ftrace_replace_code() which is called by
* ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
@@ -237,452 +163,57 @@ int ftrace_modify_call(struct dyn_ftrace
unsigned long addr)
{
WARN_ON(1);
- ftrace_expected = NULL;
return -EINVAL;
}
-static unsigned long ftrace_update_func;
-static unsigned long ftrace_update_func_call;
-
-static int update_ftrace_func(unsigned long ip, void *new)
-{
- unsigned char old[MCOUNT_INSN_SIZE];
- int ret;
-
- memcpy(old, (void *)ip, MCOUNT_INSN_SIZE);
-
- ftrace_update_func = ip;
- /* Make sure the breakpoints see the ftrace_update_func update */
- smp_wmb();
-
- /* See comment above by declaration of modifying_ftrace_code */
- atomic_inc(&modifying_ftrace_code);
-
- ret = ftrace_modify_code(ip, old, new);
-
- atomic_dec(&modifying_ftrace_code);
-
- return ret;
-}
-
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
unsigned char *new;
- int ret;
-
- ftrace_update_func_call = (unsigned long)func;
new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
-
- /* Also update the regs callback function */
- if (!ret) {
- ip = (unsigned long)(&ftrace_regs_call);
- new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
- }
-
- return ret;
-}
-
-static nokprobe_inline int is_ftrace_caller(unsigned long ip)
-{
- if (ip == ftrace_update_func)
- return 1;
-
- return 0;
-}
-
-/*
- * A breakpoint was added to the code address we are about to
- * modify, and this is the handle that will just skip over it.
- * We are either changing a nop into a trace call, or a trace
- * call to a nop. While the change is taking place, we treat
- * it just like it was a nop.
- */
-int ftrace_int3_handler(struct pt_regs *regs)
-{
- unsigned long ip;
-
- if (WARN_ON_ONCE(!regs))
- return 0;
-
- ip = regs->ip - INT3_INSN_SIZE;
-
- if (ftrace_location(ip)) {
- int3_emulate_call(regs, (unsigned long)ftrace_regs_caller);
- return 1;
- } else if (is_ftrace_caller(ip)) {
- if (!ftrace_update_func_call) {
- int3_emulate_jmp(regs, ip + CALL_INSN_SIZE);
- return 1;
- }
- int3_emulate_call(regs, ftrace_update_func_call);
- return 1;
- }
-
- return 0;
-}
-NOKPROBE_SYMBOL(ftrace_int3_handler);
-
-static int ftrace_write(unsigned long ip, const char *val, int size)
-{
- ip = text_ip_addr(ip);
-
- if (probe_kernel_write((void *)ip, val, size))
- return -EPERM;
-
- return 0;
-}
-
-static int add_break(unsigned long ip, const char *old)
-{
- unsigned char replaced[MCOUNT_INSN_SIZE];
- unsigned char brk = BREAKPOINT_INSTRUCTION;
-
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
-
- ftrace_expected = old;
-
- /* Make sure it is what we expect it to be */
- if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
-
- return ftrace_write(ip, &brk, 1);
-}
-
-static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned const char *old;
- unsigned long ip = rec->ip;
-
- old = ftrace_call_replace(ip, addr);
-
- return add_break(rec->ip, old);
-}
-
-
-static int add_brk_on_nop(struct dyn_ftrace *rec)
-{
- unsigned const char *old;
-
- old = ftrace_nop_replace();
-
- return add_break(rec->ip, old);
-}
-
-static int add_breakpoints(struct dyn_ftrace *rec, bool enable)
-{
- unsigned long ftrace_addr;
- int ret;
-
- ftrace_addr = ftrace_get_addr_curr(rec);
-
- ret = ftrace_test_record(rec, enable);
-
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
-
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return add_brk_on_nop(rec);
-
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return add_brk_on_call(rec, ftrace_addr);
- }
- return 0;
-}
-
-/*
- * On error, we need to remove breakpoints. This needs to
- * be done caefully. If the address does not currently have a
- * breakpoint, we know we are done. Otherwise, we look at the
- * remaining 4 bytes of the instruction. If it matches a nop
- * we replace the breakpoint with the nop. Otherwise we replace
- * it with the call instruction.
- */
-static int remove_breakpoint(struct dyn_ftrace *rec)
-{
- unsigned char ins[MCOUNT_INSN_SIZE];
- unsigned char brk = BREAKPOINT_INSTRUCTION;
- const unsigned char *nop;
- unsigned long ftrace_addr;
- unsigned long ip = rec->ip;
-
- /* If we fail the read, just give up */
- if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
-
- /* If this does not have a breakpoint, we are done */
- if (ins[0] != brk)
- return 0;
-
- nop = ftrace_nop_replace();
-
- /*
- * If the last 4 bytes of the instruction do not match
- * a nop, then we assume that this is a call to ftrace_addr.
- */
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) {
- /*
- * For extra paranoidism, we check if the breakpoint is on
- * a call that would actually jump to the ftrace_addr.
- * If not, don't touch the breakpoint, we make just create
- * a disaster.
- */
- ftrace_addr = ftrace_get_addr_new(rec);
- nop = ftrace_call_replace(ip, ftrace_addr);
-
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
- goto update;
-
- /* Check both ftrace_addr and ftrace_old_addr */
- ftrace_addr = ftrace_get_addr_curr(rec);
- nop = ftrace_call_replace(ip, ftrace_addr);
-
- ftrace_expected = nop;
-
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
- return -EINVAL;
- }
-
- update:
- return ftrace_write(ip, nop, 1);
-}
-
-static int add_update_code(unsigned long ip, unsigned const char *new)
-{
- /* skip breakpoint */
- ip++;
- new++;
- return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1);
-}
-
-static int add_update_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_call_replace(ip, addr);
- return add_update_code(ip, new);
-}
-
-static int add_update_nop(struct dyn_ftrace *rec)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_nop_replace();
- return add_update_code(ip, new);
-}
-
-static int add_update(struct dyn_ftrace *rec, bool enable)
-{
- unsigned long ftrace_addr;
- int ret;
-
- ret = ftrace_test_record(rec, enable);
-
- ftrace_addr = ftrace_get_addr_new(rec);
-
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
-
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return add_update_call(rec, ftrace_addr);
-
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return add_update_nop(rec);
- }
-
- return 0;
-}
-
-static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_call_replace(ip, addr);
-
- return ftrace_write(ip, new, 1);
-}
-
-static int finish_update_nop(struct dyn_ftrace *rec)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_nop_replace();
-
- return ftrace_write(ip, new, 1);
-}
-
-static int finish_update(struct dyn_ftrace *rec, bool enable)
-{
- unsigned long ftrace_addr;
- int ret;
-
- ret = ftrace_update_record(rec, enable);
-
- ftrace_addr = ftrace_get_addr_new(rec);
-
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
-
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return finish_update_call(rec, ftrace_addr);
-
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return finish_update_nop(rec);
- }
+ text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
return 0;
}
-static void do_sync_core(void *data)
-{
- sync_core();
-}
-
-static void run_sync(void)
-{
- int enable_irqs;
-
- /* No need to sync if there's only one CPU */
- if (num_online_cpus() == 1)
- return;
-
- enable_irqs = irqs_disabled();
-
- /* We may be called with interrupts disabled (on bootup). */
- if (enable_irqs)
- local_irq_enable();
- on_each_cpu(do_sync_core, NULL, 1);
- if (enable_irqs)
- local_irq_disable();
-}
-
void ftrace_replace_code(int enable)
{
struct ftrace_rec_iter *iter;
+ struct text_poke_loc *tp;
struct dyn_ftrace *rec;
- const char *report = "adding breakpoints";
- int count = 0;
- int ret;
+ const char *new;
for_ftrace_rec_iter(iter) {
rec = ftrace_rec_iter_record(iter);
- ret = add_breakpoints(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
-
- report = "updating code";
- count = 0;
-
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
-
- ret = add_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
-
- report = "removing breakpoints";
- count = 0;
-
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
-
- ret = finish_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
+ if (tp_vec_nr == TP_VEC_MAX) {
+ text_poke_bp_batch(tp_vec, tp_vec_nr);
+ tp_vec_nr = 0;
+ }
- return;
+ switch (ftrace_test_record(rec, enable)) {
+ case FTRACE_UPDATE_IGNORE:
+ continue;
+
+ case FTRACE_UPDATE_MODIFY_CALL:
+ case FTRACE_UPDATE_MAKE_CALL:
+ new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec));
+ break;
+
+ case FTRACE_UPDATE_MAKE_NOP:
+ new = ftrace_nop_replace();
+ break;
+ };
- remove_breakpoints:
- pr_warn("Failed on %s (%d):\n", report, count);
- ftrace_bug(ret, rec);
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
- /*
- * Breakpoints are handled only when this function is in
- * progress. The system could not work with them.
- */
- if (remove_breakpoint(rec))
- BUG();
+ tp = &tp_vec[tp_vec_nr++];
+ text_poke_loc_init(tp, (void *)rec->ip, new, MCOUNT_INSN_SIZE, NULL);
}
- run_sync();
-}
-
-static int
-ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code)
-{
- int ret;
-
- ret = add_break(ip, old_code);
- if (ret)
- goto out;
-
- run_sync();
-
- ret = add_update_code(ip, new_code);
- if (ret)
- goto fail_update;
-
- run_sync();
-
- ret = ftrace_write(ip, new_code, 1);
- /*
- * The breakpoint is handled only when this function is in progress.
- * The system could not work if we could not remove it.
- */
- BUG_ON(ret);
- out:
- run_sync();
- return ret;
-
- fail_update:
- /* Also here the system could not work with the breakpoint */
- if (ftrace_write(ip, old_code, 1))
- BUG();
- goto out;
}
void arch_ftrace_update_code(int command)
{
- /* See comment above by declaration of modifying_ftrace_code */
- atomic_inc(&modifying_ftrace_code);
-
ftrace_modify_all_code(command);
-
- atomic_dec(&modifying_ftrace_code);
}
int __init ftrace_dyn_arch_init(void)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -568,15 +568,6 @@ NOKPROBE_SYMBOL(do_general_protection);
dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
{
-#ifdef CONFIG_DYNAMIC_FTRACE
- /*
- * ftrace must be first, everything else may cause a recursive crash.
- * See note by declaration of modifying_ftrace_code in ftrace.c
- */
- if (unlikely(atomic_read(&modifying_ftrace_code)) &&
- ftrace_int3_handler(regs))
- return;
-#endif
if (poke_int3_handler(regs))
return;
^ permalink raw reply [flat|nested] 7+ messages in thread